There are some circumstances where you need to be able to “split tunnel” your network connection between an intranet and internet connection. This especially comes into play when you’re connected to multiple VPNs at any given time.
To absolve yourself of having your fast internet connection reduced to a crawl because it’s piped through some throttled private network, you can modify your route table.
TechNET had a great article on the split tunnel concept and how to script your own route table changes (instead of having to hack it together on the command line.)
You can read more about scripting your own split tunnel route here:
http://www.microsoft.com/technet/community/columns/cableguy/cg1003.mspx